It should be available in just about every market, not sure why WPCentral is adding (United States) to the link??? Although I'm not too sure how long it takes to populate all the markets. Edit, that's odd, just went to the UK WP site and while "UnClocked" returns no results, " Klingon Clock" finds the app.

Changelog:• Add album art from the local images.
• Force Xbox Music app to update the info after modifying the tag of the local music.
• UI and UX improvements.
• Bug fixes.
• Change trial limitation. Editing the tags of the local music is now available at trial version, but album art searching is not.